How to expand sub buttons in a vertical menu on hover?

To expand sub buttons on hover go to the menu's advanced mode. Then check the collapse & click done. 
The result is that while hover over a button all of it's sub buttons will appear.

Here is how to expand sub buttons in a vertical menu on hover:

Step 1: Enter the vertical menu's edit mode

Step 2: Click advanced

Step 3: Check the collapse check box (in red)


Note: Make sure you are on the Menu tab within General